This invention relates to methods and apparatus for opening locks and, in particular, for opening magnetic cylinder locks.
In the security industry it is frequently desirable, or necessary, to open, or "pick", a lock for which no key is available. Often keys are lost or stolen or are for some other reason unavailable at a time when they are needed, for example in an emergency when they are in the possession of someone who cannot be reached at the moment. Although many types of locks are readily picked under such conditions, the need for greater security often leads to the use of a more nearly foolproof lock which makes the job of opening the lock without a key for legitimate reasons more difficult.
One type of lock which is frequently utilized for security is a conventional cylinder lock having a fixed outer cylinder and an inner cylinder rotatably disposed within the outer cylinder and having a keyway for receiving a key to open the lock, the lock being designed such that rotation of the inner cylinder by a key will release the lock mechanism. Ordinarily the inner cylinder is held in place by an in-line series of pins disposed within respective chambers of the cylinders. Each pin has two parts placed end to end against one another within its chamber, which extends from the outer cylinder into the inner cylinder, and a spring in the outer cylinder which biases the two parts of the pin toward the inside of the inner cylinder. Without a key inserted the part of each pin against which its spring pushes straddles the sheer line between the inner and outer cylinders so that the inner cylinder cannot turn within the outer cylinder. However, when the proper key is placed within the inner cylinder ridges formed along one edge of the key displace the innermost part of each pin a predetermined amount away from the center of the inner cylinder so that the division of the two parts of each pin is positioned at the sheer line between the inner and outer cylinders, thereby permitting the inner cylinder to be rotated relative to the outer cylinder. By varying the dividing point of the two parts of each pin along the length of the pin for each pin a variety of "combinations" for such a lock can be provided.
Since the pins of such a typical cylinder lock protrude into the keyway of the inner cylinder and can be manipulated by devices placed within that keyway there are numerous ways to pick a conventional cylinder lock. With some practice, for example, such a lock may sometimes be picked merely with a bent paperclip. In addition, however, there are also more sophisticated tools for picking such a lock. One type of tool, illustrated by Moore U.S. Pat. No. 3,264,908 and Miskill U.S. Pat. No. 2,565,254, utilizes a blade for placement in the keyway and an apparatus for inducing vibration in the blade, which rapidly moves the cylinder pins in a random fashion, eventually causing the points of division of the pins to be simultaneously aligned with the sheer line so that the inner cylinder may be rotated. A similar type of device, illustrated by Segal U.S. Pat. No. 2,309,677 and Wakstein U.S. Pat. No. 1,977,362, utilizes a blade which may be inserted in the keyway of the inner cylinder and an apparatus for delivering an impact to the blade upon command, thereby moving the pins and possibly placing them in position for rotation of the inner cylinder.
A relatively new type of cylinder lock which completely resists opening by the afore-described methods and apparatus utilizes single-part magnetic pins placed within chambers in the outer cylinder and biased toward the inner cylinder by springs, and a key containing corresponding magnets which displace the pins away from the inner cylinder past the sheer line of the two cylinders so that the inner cylinder may be rotated. The inner cylinder forms a protective sleeve between the lock pins and the key so that the lock pins do not protrude into the keyway where they could be manipulated or examined by a device placed within the keyway; nevertheless, a key having the proper combination of magnets imbedded therein, the magnets being properly oriented with respect to polarity, and placed within the keyway will displace the pins due to the action of the magnetic fields. Thus, the pins cannot be manipulated into position by conventional lock picking apparatus since they are inaccessible, but the lock is readily opened by an appropriate magnetic key.
While magnetic cylinder locks of the afore-described type have the advantage of substantial security, they have the disadvantage that they are not readily openable for legitimate purposes when a key is unavailable. Accordingly, there is a need for a means for opening such a lock other than with its key.